EP1702820B1 - Cooling circuit with a retarder - Google Patents

Description

The invention relates to a cooling circuit, in particular a vehicle cooling circuit, for cooling an engine, in particular internal combustion engine, in which a hydrodynamic brake is arranged in the cooling circuit, and the cooling medium is in particular at the same time the working fluid of the hydrodynamic brake.

Such cooling circuits are known in a variety of designs. For example, on the Laid-open publication DE 196 37 316 A1 directed.

Further corresponding cooling circuits show the documents WO 95/01500 A . US 2002/148691 A1 and US Pat. No. 6,546,899 B1 ,

According to the state of the art, switching back and forth between a braking operation and a non-braking operation causes the cooling medium to flow through the hydrodynamic brake once (in braking operation), while in the other case (non-braking operation), the cooling medium bypasses the hydrodynamic brake through a bypass is directed. For this purpose, a changeover valve is provided, usually a 3/2 valve, by means of which the "incoming" cooling medium flow is conducted either through the bypass or through the hydrodynamic brake. Likewise embodiments are known in which a largely arbitrary division of the cooling medium flow to the cooling circuit branch with the hydrodynamic brake and the bypass can be carried out, comprising the two extreme states that the cooling medium is passed exclusively through the bypass or exclusively by the hydrodynamic brake.

However, the invention also relates to such cooling circuits in which the cooling medium of the cooling circuit is not passed directly through the hydrodynamic brake, but in the cooling circuit, a heat exchanger is connected by means in which a arranged in a separate circuit working fluid of the hydrodynamic brake is cooled. In particular, the hydrodynamic brake in such a case is designed as an oil retarder whose working fluid is a hydraulic oil, and the heat of the hydraulic oil heated by the oil retarder is via an oil-water heat exchanger, which is arranged with its water side in the cooling circuit, in particular vehicle cooling circuit, discharged to the cooling circuit.

Allen generic cooling circuits according to the prior art, it is meant that both the bypass and the hydrodynamic brake or the heat exchanger for cooling the working fluid of the hydrodynamic brake are arranged in a pure circuit to be cooled by the cooling medium motor in the cooling circuit, either in the flow direction the engine or in the flow direction behind the engine.

In general, a cooling medium pump is provided in such a cooling circuit, which serves to circulate the cooling medium in all switching states of the cooling circuit in this to maintain a flow circuit, so that the cooling medium on the one hand, desired components, such as the internal combustion engine and the hydrodynamic brake, and can cool on the other hand, in a heat exchanger arranged in the cooling circuit, the heat absorbed by the cooling medium can be dissipated again. In particular, when used in a vehicle, it is important to optimize the performance of the cooling medium pump to the effect that the cooling medium pump works with the highest possible efficiency in order to reduce the fuel consumption of the vehicle.

In addition, the availability of the hydrodynamic brake should be carried out as optimally as possible.

Although the previous solutions work successfully, there is room for improvement. In particular, the availability of the hydrodynamic brake should be increased further and the power consumption of the pump should be improved with regard to the different operating states of brake operation and non-braking operation.

The invention is therefore based on the object, a cooling circuit with a cooling medium pump, which pumps a cooling medium in the cooling circuit, a motor which is cooled by the cooling medium and a hydrodynamic brake whose working fluid is the cooling medium or whose working fluid is cooled by the cooling medium, in such a way that the cooling circuit with respect to the said features, retarder availability and power consumption of the pump, is improved.

The object of the invention is achieved by a cooling circuit with the features of the independent claims. The dependent claims describe advantageous and particularly expedient embodiments of the invention.

Deviating from a basic principle of the previous embodiments, according to the invention, the hydrodynamic brake or the heat exchanger for direct cooling of the working medium of the hydrodynamic brake in the cooling circuit - with respect to the cooling medium flow through the motor and the hydrodynamic brake or the corresponding heat exchanger - arranged parallel to the engine , And before the hydrodynamic brake or the heat exchanger for the hydrodynamic brake, a valve which is designed as a switch-on valve or as a switch-on control valve, with respect to the flow guide (in braking mode) also arranged parallel to the engine.

This ensures that in the non-braking operation, in which the valve is closed, the cooling medium from the cooling medium pump is pumped only by the internal combustion engine, which so to speak represents the bypass to the hydrodynamic brake, whereas in braking mode, the cooling medium flow, in particular immediately behind the cooling medium pump, is divided into two partial streams, characterized in that the valve is opened, wherein one of these two partial streams is passed through the motor and the other partial flow through the hydrodynamic brake or the heat exchanger for immediate cooling of the working fluid of the hydrodynamic brake.

In the following we describe the invention with reference to its first embodiment, in which the cooling medium is at the same time the working medium of the hydrodynamic brake, but it should be noted that it is alternatively possible to provide a separate working medium circuit for the hydrodynamic brake, for example an oil circuit for an oil retarder , And to use the cooling medium of the cooling circuit for cooling this working medium. Thus, in such an embodiment, instead of the hydrodynamic brake in the cooling circuit, a heat exchanger can be arranged.

The opening of the valve to introduce cooling medium in the transition from non-braking operation to braking operation in the hydrodynamic brake, and thus the "activation" of the second, parallel cooling medium flow relative to the cooling medium flow through the engine, has the consequence that the effective flow cross-section in the cooling circuit in braking mode is greatly increased compared to the non-braking operation, whereby the total flow resistance in the cooling circuit, which is to be overcome by the cooling medium pump, is extremely reduced. In particular, when connecting the second, parallel flow cross-section by opening the parallel branch with the hydrodynamic brake directly behind the pump an increase in the pump delivery rate is advantageously achieved. Thus, even when the hydrodynamic brake is switched on, the motor is supplied with a sufficient cooling medium flow which is not or hardly reduced in comparison with the non-braking operation, and the hydrodynamic brake can simultaneously obtain the cooling medium flow required for a high braking torque in a large flow rate. As a rule, the hydrodynamic brake will automatically be able to suck in the required cooling medium flow due to its suction effect and pump it in the direction of the heat exchanger due to its pumping action.

In particular, in a regulation of the coolant temperature to a constant engine outlet temperature, that is, the cooling medium, which from the engine exits the same after cooling, should preferably have a constant temperature, this temperature control can remain largely unaffected by a temperature overlap by the cooling medium flow from the hydrodynamic brake by the design of the cooling circuit according to the invention.

The regulation of the cooling medium temperature is advantageously carried out by providing a bypass to the heat exchanger, in particular the vehicle radiator, by means of which the heat is removed from the cooling medium to the environment, and a division of the cooling medium flow to be cooled onto the heat exchanger and the bypass. If a strong cooling of the cooling medium is required, in this split all cooling medium is passed through the heat exchanger, whereas, if no cooling is required, the cooling medium is passed completely past the heat exchanger through the bypass. Any intermediate stages of a distribution of the cooling medium flow to the heat exchanger and the bypass are conceivable.

The temperature control can suceln over a so-called thermostat control valve, that is, via a valve in the flow direction in front of the heat exchanger and the bypass around the heat exchanger, which divides the cooling medium flow to the heat exchanger and the bypass depending on the detected temperature of the inflowing cooling medium. Alternatively, it is possible to provide in the engine or in the flow direction of the cooling medium behind the engine, a thermostat or a temperature sensor for detecting the temperature of the emerging from the motor coolant, and the distribution of this cooling medium flow to the heat exchanger and the bypass via an additionally provided valve, for example a changeover valve behind or in front of the heat exchanger to provide. The detection of the temperature can also be done indirectly, for example via a temperature sensor positioned elsewhere or by calculation from other detected state variables.

According to an advantageous embodiment of the invention, the cooling medium originating from the hydrodynamic brake is always passed completely through the heat exchanger in braking operation, that is, the cooling medium flow from the hydrodynamic brake is not influenced or regulated by the described control device for dividing the cooling medium flow to the heat exchanger and the bypass ,

According to an alternative embodiment, the cooling medium flow from the hydrodynamic brake can be divided by a separate control device into two partial flows, for example also by a thermostatic control valve, wherein a partial flow is passed directly towards the heat exchanger, and the other partial flow in the direction of the control device for the division the cooling medium flow from the internal combustion engine and in this case in addition to the cooling medium flow supplied to the heat exchanger and the bypass is passed to the heat exchanger.

In particular, the additional thermostatic control valve may have a lower switching point than the first thermostatic control valve, which, in particular when it is arranged on the engine, for example, alone due to heat conduction of heat generated in the engine is already open when the engine operating temperature to all Cooling medium from the hydrodynamic brake directly fed to the heat exchanger, whereas at least indirectly, for example, in conjunction with another thermostatic control valve, cooling medium from the hydrodynamic brake passes the heat exchanger over to quickly by a higher temperature of the medium in the cooling medium cycle the engine to operating temperature bring as long as the engine has not yet reached.

According to an advantageous embodiment, in the parallel to the engine branch of the cooling circuit, in which the hydrodynamic brake is arranged, in addition to the switch-on valve to connect the hydrodynamic brake in braking mode, a separate control valve is arranged. hereby Pressure surges can be avoided when switching on the hydrodynamic brake by interaction of the on-off valve and control valve. For example, the control valve can be throttled or closed during the switch-on, whereas it is opened during the switch-off after a previous throttling.

A in the parallel to the engine branch of the cooling circuit in which the hydrodynamic brake is arranged, in addition to the on-valve arranged control valve in the flow direction behind the hydrodynamic brake can also be used to control the supplied from the hydrodynamic brake braking torque or to regulate.

The solution according to the invention optimizes the cooling medium flow through the hydrodynamic brake. The power consumption of the cooling medium pump only increases during braking operation, that is to say in an operating state in which a power consumption is desired in any case in order to decelerate the motor, because it drives the cooling medium pump.

Another advantage is the fact that cools the non-braking operation in the parallel cooling circuit branch with the hydrodynamic brake cooling medium and thus exerts an additional cooling effect when switching from non-braking operation to the braking operation on the entire cooling circuit.

In particular, by directly introducing the derived from the hydrodynamic brake cooling medium flow in the heat exchanger, the availability of the hydrodynamic brake can be increased by a higher heating of the cooling medium in the hydrodynamic brake, especially during the period in which the engine after a cold start to operating temperature is brought, compared to conventional embodiments, in which the cooling medium from the hydrodynamic brake directed to the temperature control device and thus partially passed on the heat exchanger, because the temperature control device for heating the engine wants to avoid cooling of the cooling medium.

The direct introduction of the derived from the hydrodynamic brake cooling medium flow in the heat exchanger further increases the availability of the hydrodynamic brake in that the inertia of a thermostatic control valve, which is used for temperature control or regulation of the cooling medium, not on the derived from the hydrodynamic brake cooling medium Has influence. When supplying this cooling medium to a corresponding thermostatic control valve conventionally, the inertia of this valve can cause a switching of the cooling medium from the bypass to the heat exchanger takes place only with delay, and thereby an undesirable increase in the temperature of the cooling medium occurs.

The invention will be explained in more detail with reference to embodiments and the figures.

Figur 1

ein erstes Ausführungsbeispiel der Erfindung mit einem Thermostat-Regelventil und der unmittelbaren Zuführung des Kühlmediumstroms aus der hydrodynamischen Bremse in den Wärmetauscher;

Figur 2

ein Ausführungsbeispiel mit zwei Thermostat-Regelventilen;

Figur 3

ein Ausführungsbeispiel der Erfindung mit einer abgewandelten Temperaturregelung;

Figur 4

ein Ausführungsbeispiel gemäß der Figur 3, wobei jedoch das Einschalt-Ventil als Regelventil ausgebildet ist;

Figur 5

ein Ausführungsbeispiel mit einem Ölretarder;

Figur 6

die Anordnung eines Drehflügels im Kühlkreislauf an der Verzweigungsstelle, in welcher das Kühlmedium in Richtung des Motors und des Retarders aufgeteilt wird.

Show it:

FIG. 1

a first embodiment of the invention with a thermostat control valve and the direct supply of the cooling medium flow from the hydrodynamic brake in the heat exchanger;

FIG. 2

an embodiment with two thermostatic control valves;

FIG. 3

an embodiment of the invention with a modified temperature control;

FIG. 4

an embodiment according to the FIG. 3 However, wherein the on-valve is designed as a control valve;

FIG. 5

an embodiment with an oil retarder;

FIG. 6

the arrangement of a rotary vane in the cooling circuit at the branch point, in which the cooling medium is divided in the direction of the motor and the retarder.

In the FIG. 1 can be seen a cooling circuit of a motor vehicle, wherein in the cooling circuit, a cooling medium pump 1 is arranged in the flow direction immediately behind the heat exchanger 2 and the bypass 6 to the heat exchanger around. The cooling medium flow is divided immediately after the cooling medium pump 1 - in braking mode - into two partial flows, one of which flows through the conduit 13, and the other through the conduit 14. The conduit 14 is passed through the engine 3, which is designed as an internal combustion engine , so that the cooling medium flow through the line 14 cools the motor 3. The engine 3 drives via a gear 12 to the hydrodynamic brake 4, which is presently designed as Sekundärwasserretarder, that is, the hydrodynamic brake 4 is arranged in the power flow of the drive train of the vehicle gear output side and used as working fluid water or a water mixture, namely the cooling medium of the vehicle cooling circuit ,

The line 13 leads via a switch-on valve 5, that is to say via a valve which has only two positions, namely a first position in which it is fully open and a second position in which it is completely closed, to the hydrodynamic one Brake 4, which thus can be switched on and off by pressing the valve 5, characterized in that their working space is filled and emptied.

In the flow direction behind the hydrodynamic brake 4, an additional control valve 10 is arranged to control the flow rate through the parallel to the motor 3 line branch of the cooling circuit, with the on-valve 5, the hydrodynamic brake 4 and just this control valve 10.

Starting from the control valve 10, the cooling medium is transferred from the hydrodynamic brake via the line 15 in a line 16, which leads directly to the heat exchanger 2.

The cooling medium through the motor 3 in the conduit 14, that is parallel to the conduit 15, is directed to a thermostatic control valve 8, which divides this cooling medium flow into two partial streams, of which a partial flow flows via the conduit 16 into the heat exchanger 2, and the other partial flow via the line 6 on the heat exchanger 2 over to the pump 1 flows. The thermostatic control valve thus alone forms the control device 7 for dividing the cooling medium flow and for temperature control in the cooling circuit.

To compensate for volume fluctuations in the cooling circuit, a surge tank 11 is provided in a known manner.

How to get out of FIG. 1 clearly recognizes, when switching on the hydrodynamic brake 4, that is, the transition from non-braking operation to braking operation or when opening the on-valve 5, the effective flow area compared to the non-braking operation in the cooling circuit significantly increased. While in non-braking mode, all the cooling medium alone has to flow through the line 14, this cooling medium flow is divided in the braking mode to the lines 13 and 14, which together provide a larger flow cross-section available. At the same time, the hydrodynamic brake 4, which is driven via the gear 12, operates as a pump, so that in addition to the cross-sectional widening in the coolant circuit in addition to a reduction in the total flow resistance in the cooling circuit, which must be overcome by the cooling medium pump 1 contributes. As a result, the amount of cooling medium delivered by the cooling medium pump 1 increases, which is desirable during braking operation.

According to the FIG. 2 is in the line 15, a second thermostat control valve 9 is provided which the cooling medium flow from the line 15, that is from the hydrodynamic brake 4, divided into two partial streams. The first partial flow is passed directly into the conduit 16 and thus the heat exchanger 2, while the second partial flow is directed into the conduit 14 and to the first thermostatic control valve 8. In the context of the present invention, the division of a medium flow into two partial flows also includes the two extreme states, in which either the incoming medium flow is completely assigned to the first partial flow or the incoming medium flow is completely assigned to the second partial flow.

By providing the second thermostatic control valve, it is possible, for faster heating of the motor 3 after a cold start, the coolant flow originating from the hydrodynamic brake 4, instead of directing it directly to the heat exchanger 2, in the direction of the first thermostatic control valve 8 and via this pass past the heat exchanger 2 through the bypass 6.

The second thermostatic control valve 9 may for example be designed with an extremely low switching point and be arranged in heat-conducting connection with the motor 3, so that only when the engine 3 has not reached its operating temperature, the cooling medium flow from the hydrodynamic brake 4th partially or completely leads in the direction of the first thermostatic control valve 8 or generally mixed with the cooling medium flow from the internal combustion engine 3, whereas it, as soon as the engine 3 has reached its operating temperature, all cooling medium from the hydrodynamic brake 4 directly to the heat exchanger 2 zuleitet so that This cooling medium can not be bypassed by the bypass 6 to the heat exchanger 2.

According to the FIGS. 3 to 5 is the control device 7 for dividing the cooling medium flow from the motor 3 in a partial flow in the direction of the heat exchanger 2 and a partial flow through the bypass 6 on the heat exchanger 2 over by deviating from the in the Figures 1 and 2 illustrated embodiments designed. Thus, the control device 7 comprises a switching valve 7.1 in the flow direction behind the heat exchanger and a thermostat or a temperature sensor 7.2 for detecting the temperature of the effluent from the engine 3 cooling medium. The switching valve 7.1 interrupts the cooling medium flow from the heat exchanger 2 in a first position, so that all the cooling medium is conducted past the heat exchanger 2 through the bypass 6. In its second position, the switching valve 7.1 interrupts the cooling medium flow through the bypass 6, so that all cooling medium is passed through the heat exchanger 2. The valve 7.1 is advantageously designed as a control valve, so that intermediate positions, in particular any intermediate positions, between the two said positions are possible to achieve a division of the cooling medium flow through the heat exchanger 2 and at the same time by the bypass 6 in desired proportions.

In the FIGS. 3 and 4 is in the flow direction behind the hydrodynamic brake 4, as in the in the Figures 1 and 2 shown embodiments, a control valve 10 is arranged.

According to the FIG. 4 In addition, the valve 5 is in the flow direction before the hydrodynamic brake designed as a switch-control valve, so that this not only completely allow the cooling medium flow into the hydrodynamic brake 4 or interrupt, but intermediate positions are possible to throttle or regulate this cooling medium flow.

In the FIG. 5 Furthermore, the alternative embodiment of the invention is shown in which the hydrodynamic brake is not directly in the cooling circuit in which the cooling medium circulates, is arranged. Instead, instead of the hydrodynamic brake 4 in the preceding embodiments, a heat exchanger 17 is arranged, whose water side is cooled by the cooling medium. By means of the heat exchanger 17, also referred to as a heat exchanger of the hydrodynamic brake, the working medium of hydrodynamic brake 4, which is present oil, since the hydrodynamic brake 4 is designed as an oil retarder, cooled. Moreover, the features of the invention described above, however, can be applied unchanged, since it is just as necessary to cool the hydrodynamic brake 4 in braking mode, which is here not deviating directly, but indirectly achieved via the additional heat exchanger 17.

In the FIG. 6 a flow cross-section control device 18 is shown, which is arranged in the branch point of the cooling circuit, in which the cooling medium flow from the pump 1 is divided into two partial streams, of which a partial flow in the direction of the motor 3 and the other partial flow in the direction of the hydrodynamic brake 4 and corresponding heat exchanger 17 is passed. The flow cross-section control device 18, which is shown only schematically in the form of a rotary vane, opens the flow cross section in the direction of the engine 3 as long as the cooling circuit branch is closed with the hydrodynamic brake 4. In braking mode, on the other hand, the flow cross-section control device 18 restricts the flow cross-section in the direction of the engine 3 by a desired amount and thus ensures the optimum distribution of the cooling medium between the engine 3 and the hydrodynamic brake 4.

Claims (8)

1. A cooling circuit, especially a vehicle cooling circuit, comprising

   1.1 a cooling medium pump (1) which recirculates a cooling medium in the cooling circuit;

   1.2 a heat exchanger (2) for dissipating heat from the cooling medium;

   1.3 a motor (3) which is cooled by the cooling medium;

   1.4 a hydrodynamic brake (4) whose working medium is the cooling medium or whose working medium is cooled by the cooling medium in an additional heat exchanger (17);

   1.5 a valve (5) for switching the hydrodynamic brake (4) into the cooling circuit in a braking operation and for switching the hydrodynamic brake (4) out of the cooling circuit in a non-braking operation;

   1.6 the hydrodynamic brake (4) or the additional heat exchanger (17) is arranged in the cooling circuit parallel to the motor (3) with respect to the cooling medium flow, and

   1.7 the valve (5) is arranged as a switch-on valve or switch-on control valve and is arranged in the direction of flow before the hydrodynamic brake (4) or the additional heat exchanger (17) and parallel to the motor (3); characterized by the following features:

   1.8 the cooling circuit is divided directly behind the cooling medium pump (1) into a first branch with the motor (3) and a second branch with the hydrodynamic brake (4) or the additional heat exchanger (17), which second branch is parallel to the first branch, with

   1.9 a bypass (6) parallel to the heat exchanger (2) being provided and a control apparatus (7) for dividing the cooling medium flow in order to guide a portion of the cooling medium or the entire cooling medium past the heat exchanger (2), with the cooling medium guidance for cooling medium from the motor (3) being switched with the heat exchanger (2), the bypass (6) and the control apparatus (7) in such a way that the cooling medium from the motor (3) can be guided partly or completely through the heat exchanger (2) or past the same by means of the control apparatus (7), whereas

   1.10 a cooling medium guidance for cooling medium from the hydrodynamic brake (4) or the additional heat exchanger (17) is switched together with the heat exchanger (2) in such a way that the cooling medium is guided from the hydrodynamic brake (4) or the additional heat exchanger (17) always completely through the heat exchanger (2).
2. A cooling circuit, especially a vehicle cooling circuit, comprising

   2.1 a cooling medium pump (1) which recirculates a cooling medium in the cooling circuit;

   2.2 a heat exchanger (2) for dissipating heat from the cooling medium;

   2.3 a motor (3) which is cooled by the cooling medium;

   2.4 a hydrodynamic brake (4) whose working medium is the cooling medium or whose working medium is cooled by the cooling medium in an additional heat exchanger (17);

   2.5 a valve (5) for switching the hydrodynamic brake (4) into the cooling circuit in a braking operation and for switching the hydrodynamic brake (4) out of the cooling circuit in a non-braking operation;

   2.6 the hydrodynamic brake (4) or the additional heat exchanger (17) is arranged in the cooling circuit parallel to the motor (3) with respect to the cooling medium flow, and

   2.7 the valve (5) is arranged as a switch-on valve or switch-on control valve and is arranged in the direction of flow before the hydrodynamic brake (4) or the additional heat exchanger (17) and parallel to the motor (3);
   characterized in that

   2.8 a bypass (6) is provided parallel to the heat exchanger (2), and a first thermostatic control valve (8) is arranged behind the motor (3) in the direction of flow of the cooling medium, which valve divides the cooling medium flow in the direction of the heat exchanger (2) and in the direction of the bypass (6) depending on the temperature of the cooling medium supplied from the motor (3), and

   2.9 a second thermostatic control valve (9) is arranged in the direction of flow behind the hydrodynamic brake (4) or the additional heat exchanger (17), which valve divides the cooling medium flow directly in the direction of the heat exchanger (2) and in the direction of the thermostatic control valve (8) depending on the temperature of the cooling medium supplied from the hydrodynamic brake (4) or the additional heat exchanger (17).
3. A cooling circuit according to claim 2, characterized in that the cooling circuit is divided directly behind the cooling medium pump (1) into a first branch with the motor (3) and a second branch with the hydrodynamic brake (4) or the additional heat exchanger (17), which second branch is parallel to the first branch.
4. A cooling circuit according to claim 1, characterized in that a thermostatic control valve (8) is arranged as a control apparatus (7) in the direction of flow of the cooling medium behind the motor (3), which valve divides the cooling medium flow in the direction of the heat exchanger (2) and in the direction of the bypass (6) depending on the temperature of the cooling medium supplied from the motor (3), and further in that the cooling medium is guided from the hydrodynamic brake (4) or the additional heat exchanger (17) past the thermostatic control valve (8) into the heat exchanger (2).
5. A cooling circuit according to one of the claims 1 to 4, characterized in that the valve (5) is arranged as an open-close valve.
6. A cooling circuit according to one of the claim 1 to 5, characterized in that an additional control valve (10) is provided in the direction of flow before and/or behind the hydrodynamic brake (4) or the additional heat exchanger (17) parallel to the motor (3).
7. A cooling circuit according to one of the claims 1 to 6, characterized in that the cooling circuit is a vehicle cooling circuit, the motor (3) is an internal combustion engine, and the hydrodynamic brake (4) is arranged as a secondary water retarder.
8. A cooling circuit according to one of the claims 1 to 7, characterized in that the cooling circuit is a vehicle cooling, the motor (3) is an internal combustion engine, and the hydrodynamic brake (4) is arranged as an oil retarder whose working medium of oil is cooled in the additional heat exchanger (17) by the cooling medium of the vehicle cooling circuit.

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